共查询到20条相似文献,搜索用时 62 毫秒
1.
H. Okazaki T. Arakane T. Sato T. Wakita M. Hirai Y. Takano S. Iriyama T. Yokoya 《Journal of Physics and Chemistry of Solids》2011,72(5):582-584
We studied the electronic structure evolution of heavily B-doped diamond films across the metal-insulator transition (MIT) using ultraviolet photoemission spectroscopy (UPS). From high-temperature UPS, through which electronic states near the Fermi level (EF) up to ∼5kBT can be observed (kB is the Boltzmann constant and T the temperature), we observed the carrier concentration dependence of spectral shapes near EF. Using another carrier concentration dependent UPS, we found that the change in energy position of sp-band of the diamond valence band, which corresponds to the shift of EF, can be explained by the degenerate semiconductor model, indicating that the diamond valence band is responsible for the metallic states for samples with concentrations above MIT. We discuss a possible electronic structure evolution across MIT. 相似文献
2.
G. Indlekofer P. Oelhafen J. Krieg R. Lapka U. M. Gubler H. J. Güntherodt V. L. Moruzzi H. R. Khan K. Lüders 《Zeitschrift für Physik B Condensed Matter》1985,58(4):293-297
The electronic structure of V
x
Mo1–x
(x=0.2; 0.4; 0.6; 0.75) solid solutions was studied by XPS and UPS. The density of states at the Fermi energy,N(E
F), deduced from these measurements, shows a minimum as a function of the alloy concentration on the Mo rich side. This behaviour can be explained by band structure calculations and is in good agreement with previous NMR measurements. The relation between the electronic structure at the Fermi level and the superconducting properties is discussed. The band structure of the Mo rich alloys can be understood in terms of a rigid band model. 相似文献
3.
S. A. Uporov N. S. Uporova V. E. Sidorov A. Mikula P. Terzieff 《Journal of Experimental and Theoretical Physics》2009,109(2):269-273
The magnetic susceptibility of Bi100 − x
Mn
x
(x = 5, 7.5, 10, 12.5, 15, 17.5, 20, 25) alloys is experimentally studied by the Faraday method in the temperature range T = 300−1200°C and the magnetic-field range B = 0.6−1.3 T. To calculate the electronic characteristics of the Bi-Mn alloys, the experimental results are approximated by
the generalized Curie-Weiss law. The calculated parameters of the electronic structure of the alloys demonstrate that manganese
is present in the melt in an ionic state with an effective magnetic moment μeff ≈ 5μB, all Bi-Mn alloys have negative paramagnetic temperatures (which indicate the antiferromagnetic character of the exchange
between transition 3d element atoms), and the density of states near the Fermi level n(E
F) is low. Therefore, the Fermi level is outside the d band of manganese and its position is controlled by the sp band of bismuth. 相似文献
4.
In the monovalent metals the electronic band structure is strongly affected by the size of the band gap E s-E p at the Brillouin zone faces, a large gap implying a large distortion of the Fermi surface. Here E s and E p are the energies of the purely s-like and p-like states on the zone faces. We have made crude estimates of E s-E p for the alkali and noble metals, in terms of the s-p excitation energy Δsp of the free atoms. These suggest a single model which correlates most of the experimental information about the band structures of these metals. In particular the Fermi surface of lithium appears to make considerable contact with the zone faces. In the α-phase alloys of the noble metals, the solute always has a larger value of Δsp than the solvent, which raises the energy E p relative to E s. The Fermi surface becomes more nearly spherical in copper alloys than in copper, since E p<E s, whereas it distorts further in the gold alloys (E p>E s). This accounts for many Knight shift, electronic specific heat, magnetic susceptibility and other data on these alloys. Furthermore it provides the extension of Jones' explanation of the Hume-Rothery rule demanded by the non-spherical Fermi surface in pure copper and gold. 相似文献
5.
Xiao-Ping WeiShi-Bing Chu Ge-Yong MaoHong Deng Tao LeiXian-Ru Hu 《Journal of magnetism and magnetic materials》2011,323(17):2295-2299
We investigate the electronic structures and magnetic properties of Mn2ZnMg compound with Hg2CuTi-type structure using first-principles full-potential local orbital minimum basis calculations. Based on the analysis on the electronic structures, it is demonstrated that the compound is half-metallic antiferromagnet and the compound is favorable to form Hg2CuTi-type structure instead of the conventional L21 one. The complicated hybridization among the p and d states dominates mainly the origin of the gap. The Fermi level (EF) shifts slightly with the lattice parameter changed. Spin-orbit coupling hardly reduces the degree of spin polarization of the density of states at the Fermi level. 相似文献
6.
Quantum states of 2D electrons are studied in a periodic potential without inversion center in the presence of a magnetic field. It is shown that the energy spectrum in magnetic subbands is not symmetric about the center of magnetic Brillouin zone E(k)≠E(?k). Singularities (phase branching points) of the electron wave function, which determine the quantization law of Hall conductivity σxy, are studied in the k space. It is found that a sharp change takes place in the number of points in the magnetic Brillouin zone and in the corresponding values of topological invariants determining the Hall conductivity of filled subbands. It is noted that the longitudinal conductivity of a lattice without inversion center placed in a magnetic field is not invariant with respect to a change in sign of the electric field, and a photovoltaic effect must arise in an ac electromagnetic field. 相似文献
7.
A. Bansil M. Lindroos S. Sahrakorpi R.S. MarkiewiczG.D. Gu J. Avila L. Roca A. Tejeda M.C. Asensio 《Journal of Physics and Chemistry of Solids》2002,63(12):2175-2180
We discuss first-principles simulations of angle-resolved photoemission (ARPES) intensity in Bi2212 where the photoexcitation process is modeled realistically by taking into account the full crystal wavefunctions of the initial and final states in the presence of the surface. Some recent results aimed at understanding the effects of the energy and polarization dependencies of the ARPES matrix element are presented. The nature of the Fermi surface (FS) maps obtained via ARPES by holding the initial state energy fixed at the Fermi energy (EF) is clarified. The theoretically predicted FS map at 21 eV photon energy displays a remarkable level of agreement with the corresponding ARPES spectrum taken over a large area of the (kx,ky) plane. Our analysis shows how the ARPES matrix element can help disentangle closely spaced energy levels and FS sheets and highlight different aspects of the electronic spectrum in complex materials under various experimental conditions. 相似文献
8.
V. D. Borman M. A. Pushkin V. N. Tronin V. I. Troyan 《Journal of Experimental and Theoretical Physics》2010,110(6):1005-1025
The electronic properties of nanoclusters of transition (Ni, Co, Cr) and noble (Au, Cu) metals deposited on the surface of
highly oriented pyrolytic graphite (HOPG) are studied using the method of X-ray photoelectron spectroscopy. The laws of variation
of a change ΔE
b in the binding energies of core-level electrons in the initial (ΔE
i) and final (ΔE
f) states of atoms in nanoclusters, the intrinsic widths γ of photoelectron lines, and their singularity indices α as functions
of the metal cluster size d are determined. A qualitative difference in behavior of the ΔE
i(d) and α(d) values in metals of the two groups (Ni, Cr versus Co, Cu) is found. The values of the final-state energy (ΔE
f < 0) and the line width (Δγ > 0) in the clusters of all metals studied vary in a similar manner. It is shown that a significant
contribution to E
i is due to a transfer of the valence-shell electrons at the cluster-substrate interface, which is caused by the contact potential
difference. The value of an uncompensated charge per nanocluster is determined as a function of the cluster size and the number
of atoms in the cluster. The behavior of ΔE
f(d) is controlled by the Coulomb energy of a charged cluster and by a decrease in the efficiency of electron screening, which
is different in the metals studied. The broadening of photoelectron lines is determined by a spread of the cluster sizes and
by lower electron screening in the final Fermi system. An asymmetry of the core-level electron spectra of nanoclusters can
be explained using notions about the electron-hole pair excitation near the Fermi level. The effect of the structure of the
density of electron states in the d band of transition metals on the asymmetry of photoelectron lines is considered and it is concluded that this structure near
the Fermi level qualitatively changes with a decrease in the nanocluster size. The obtained results indicate that the behavior
of the electron subsystem of clusters of the d-metals in a size range of 2–10 nm under consideration is close to the behavior of a normal Fermi system. 相似文献
9.
The electronic band structure and magnetic properties of iron phthalocyanine (FePc) monolayer were investigated by using the first-principles all-electron full-potential linearized augmented plane wave energy band method. It is found that the ferromagnetic FePc monolayer is energetically more stable than the paramagnetic one. The exchange interaction, which splits the majority and minority bands, influences strongly on the electronic structure near the Fermi level (EF). Magnetic moment of the central Fe atom is calculated to 1.95 μB. The range of the positive polarization of Fe site is larger in the out-of-plane than in the in-plane direction. The FePc ligand remains paramagnetic. The presence of states at EF indicates the metallic character of FePc monolayer both for the paramagnetic and ferromagnetic states. However, the large density of states at EF of the majority spins in the ferromagnetic state is expected to cause a phase transition to insulating antiferromagnetic state from the metallic ferromagnetic one. 相似文献
10.
E. Z. Kuchinskii I. A. Nekrasov N. S. Pavlov 《Journal of Experimental and Theoretical Physics》2013,117(2):327-337
We propose a generalization of the LDA + DMFT + Σ k approach to the multiband case, in which correlated and uncorrelated states are present in the model simultaneously. Using the multiband version of the LDA + DMFT + Σ k approach, we calculate the density of states and spectral functions for the Emery model in a wide energy interval around the Fermi level. We also obtain the Fermi surfaces for the electron-doped high-temperature superconductor Nd2 ? x Ce x CuO4 in the pseudogap phase. The self-energy part Σ k introduced additionally to take into account pseudogap fluctuations describes the nonlocal interaction of correlated electrons with collective Heisenberg short-range spin fluctuations. To solve the effective impurity model, the numerical renorm-group (NRG) method is used for the DMFT equations. Good qualitative agreement of the Fermi surfaces calculated using the LDA + DMFT + Σ k approach and experimental angle-resolved photoemission spectroscopic data is attained. The stability of the dielectric solution with charge transfer in the Emery model with correction for double counting is analyzed in the Appendix. 相似文献
11.
S. G. Ovchinnikov L. V. Burkova V. A. Seredkin V. Yu. Yakovchuk 《Physics of the Solid State》1999,41(1):80-86
A study is reported of the structural, magnetic, and magneto-optic properties of Mn/Dy/Bi films obtained by multilayer technology.
The maximum Kerr rotation angle in such films is shown to be θ
k
=2.25°. Possible reasons for such a large Kerr effect enhancement are considered, namely, an increase in the 6p–3d transition probability caused by symmetry distortion, polarization of the Bi6p band, and a change in the density of states near the Fermi level. The latter reason has been analyzed by simulating the electronic
structure of Mn/Dy/Bi through superposition of Dy levels on the MnBi band structure. This approach has revealed possible additional
transitions which may be induced by the presence of a Dy buffer and could contribute to the Kerr magneto-optic effect.
Fiz. Tverd. Tela (St. Petersburg) 41, 91–97 (January 1999) 相似文献
12.
B.-T. Wang W. Yin W.-D. Li F. Wang 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,80(3):307-310
We systematically study the structural, electronic, and magnetic
properties of chromium sulfide Y2CrS4 by using
density-functional theory. We find that antiferromagnetic order is
more energetically favorable than ferromagnetic state and near the
Fermi level the main occupation is from Cr 3d states. 相似文献
13.
Dr. M. C. Jones 《Zeitschrift für Physik B Condensed Matter》1969,9(1-2):98-103
Using the iterative solution to the Boltzmann equation for electrons in d.c. electric and magnetic fields, an expression for
the resistivity tensor can be obtained in the form of an infinite series. This series can be approximated by retaining only
the first two terms. In the cases where relaxation times exist — in the sense that the collision term in the Boltzmann equation
can be written asg(k)/τ(k), whereτ(k) is the relaxation time, andf (k) = f
E(ɛ k) + [∂f
E(εk)/∂ε]·g(k) the distribution function for electrons with wavevectork — this approximation is exact. For polyvalent metals in the one-OPW approximation, the complete galvanomagnetic tensor can
be obtained using this approximation and the result differs from that obtained by using a time of relaxation given by an expression
suggested byZiman. A calculation for a simple model Fermi surface, with screened Coulomb scattering, is carried out and the results compared
with those of the relaxation time approximation. 相似文献
14.
We present an XPS and UPS study of crystalline Co, Co3B and Co78P14B8 glassy metal. For Co3B the electronic distribution curves (EDC) of the valence band and the previous specific heat and magnetic results are interpreted in a qualitative model where : i) the s-p cobalt-boron bonding states lie in the low part of the band, the upper levels being mainly cobalt d states and ii) a large density of states of the majority spin band is present at the Fermi level. For amorphous Co78P14B8 the EDC shows that EF is located in a high density of states region, it is suggested that the phosphorus p states ae centred at 7.5 eV. The photoemission and the magnetic results can be also interpreted in the framework of the previous model. 相似文献
15.
A. Ślebarski A. Jezierski M. Neumann S. Plogmann 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(4):519-523
The electronic structure of the Co2-xZrSn Heusler alloys has been studied by X-ray photoelectron spectroscopy (XPS). XPS valence band spectra can be compared with
ab initio electronic structure calculations using the linearized muffin-tin orbital (LMTO) method. The calculated magnetic moments
per Co atom agree well with the moments obtained from experiment. The LMTO calculations also show the energy shifts of the
Co, Zr and Sn valence electron states towards the Fermi level when the concentration of vacancies increases in these alloys.
Received 9 March 1999 and Received in final form 6 May 1999 相似文献
16.
G. Seibold F. Becca F. Bucci C. Castellani C. Di Castro M. Grilli 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(1):87-97
The concept of frustrated phase separation is applied to investigate its consequences for the electronic structure of the
high T
c
cuprates. The resulting incommensurate charge density wave (CDW) scattering is most effective in creating local gaps in k-space when the scattering vector connects states with equal energy. Starting from an open Fermi surface we find that the
resulting CDW is oriented along the (10)- and (or) (01)-direction which allows for a purely one-dimensional or a two-dimensional
“eggbox type” charge modulation. In both cases the van Hove singularities are substantially enhanced, and the spectral weight
of Fermi surface states near the M-points, tends to be suppressed. Remarkably, a leading edge gap arises near these points, which, in the eggbox case, leaves
finite arcs of the Fermi surface gapless. We discuss our results with repect to possible consequences for photoemission experiments.
Received 14 June 1999 相似文献
17.
T. Schaub J. Delahaye C. Berger H. Guyot R. Belkhou A. Taleb-Ibrahimi Y. Calvayrac 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,20(2):183-188
High resolution photoemission measurements performed at low temperatures on a single-grained sample of the AlPdMn icosahedral
phase show that the density of states N(E) strongly depends on the nature of the surface. For an ordered quasicrystalline surface, prepared by Ar etching and ultra
high vacuum annealing, a dip feature is observed in N(E) near the Fermi level, which energy dependence can be analyzed with a simple square-root power law. By contrast, N(E) varies only little with energy both for a disordered surface and a crystalline surface of the same sample. A sharp Fermi
edge is then clearly observed. This shows that the metallic character of the surface of a quasicrystal is strongly reduced
when the surface presents a quasicrystalline ordering.
Received 19 February 2000 and Received in final form 6 November 2000 相似文献
18.
Based on first-principles calculations within density functional theory, we studied the effects of Cr adsorption on the electronic and magnetic properties of Bi2Se3 topological insulators employing spin–orbit coupling (SOC) self-consistently. Cr atom induces a spin-polarization with total net magnetic moments of 2.157 μB (spin up). There is a p-d hybridization between the Cr 3d states and the nearest neighbor Se 4p states. A peak of density of states appears at Fermi level. The electronic structures change and the energy levels split near the Fermi level. No gap opening has been found at the Dirac point of the surface state from the bottom surface. 相似文献
19.
A three-step model for inverse photoemission (bremsstrahlung spectroscopy) is developed in analogy to the well known corresponding model for photoemission. It is shown under which conditions bremsstrahlung spectra measure the density of the final state above the Fermi level. Data on polycrystalline nickel can be interpreted consistently when contributions due to indirect (k non-conserving) radiative transitions are taken into account as well as direct (k-conserving) transitions. 相似文献
20.
The electronic band structure of La2CuO4 is performed using self-consistent linear muffin-tin orbital method. The 17 band complex is found to arise mainly from the
overlap between Cu-3d and O-2p wavefunctions. The calculated density of states at the Fermi energy (N
E
F), the conduction band-width and the electronic specific heat coefficient are given. 相似文献